When it comes to landing in low visibility, the instrument landing system (ILS) at Green Airport is one of the best. It is said to be superior to the system at New York’s busy LaGuardia. It has a Category 3 designation, the highest.

But during the last week, dozens of flights have been diverted from Green, causing passengers to wait at airports elsewhere in the country until Rhode Island rain and fog clear away. In addition, a number of flights have been canceled outright and that has the compound effect of canceling outgoing flights because those planes never landed here.

Airport traffic numbers for May are certain to reflect the impact.

Causing the problem, apart from the weather, has been the failure of an antenna used to establish the glide slope on Runway 23; the approach that brings in planes over Airport Road. Seemingly, if weather conditions allow for it, aircraft could use Runway 5 that would take planes in over Main Avenue or the shorter crosswind runway.

But that’s not the case.

That’s because another piece of equipment essential to informing pilots whether they are left or right of the runway, called a localizer, is being moved about 200 feet to get it out of the Runway 5 safety area. Even though the Runway 5 glide slope works, it can’t be used for instrument landings without the localizer. The antenna informs the pilot whether the plane is on the correct trajectory to touchdown at the end of the runway.

A Federal Aviation Administration (FAA) spokesman said Tuesday that work on relocating the localizer started May 2 and should be done in another two weeks.

What about the crosswind runway; why couldn’t it be used?

Runway 16, which comes in over Ann & Hope, does not have an ILS. Coming from the opposite direction over Sandy Lane, Runway 34 is a Category 1 system, meaning it can’t be used once visibility drops below 1,200 feet.

The convergence of repairs to the localizer, the failed antenna and reduced visibility caused 11 diversions and four canceled flights last Wednesday, Rhode Island Airport Corporation President Kevin Dillon said Monday. He also reported that the antenna had been repaired for Runway 23, seemingly reducing the possibility that the airport would be shut down for low visibility in the near future.

But this Tuesday there was another round of diversions and cancellations.

The antenna had been repaired, but in order to be activated, it needed a flight check. The FAA had not done that, even though the skies were clear over the weekend.

“As soon as weather conditions permit, the FAA expects to flight check the Instrument Landing System for Runway 23 at T.F. Green Airport to ensure that the equipment is working properly after recent repairs. Bad weather over the last several days has delayed the flight check,” the FAA responded. Further, it was pointed out that the check must be scheduled because the planes that do that work are based in Oklahoma City.

Dillon was hopeful the flight check could be performed Wednesday if the weather permits.

Even when the localizer is back up and working, it will be some time before Runway 5 is restored to a Category 3 system. When first initiated, the runway will be a Category 1 system and only after a “burn in” of about 1,000 hours can it regain its superior Category 3 status.

During diversions, Dillon explained, planes scheduled to arrive at Green are directed to other airports where they will wait for improved weather conditions before resuming their flights. Cancellations are more problematic because the arriving plane is not here for an outgoing flight.

RIAC has failed to post its passenger counts for March, yet it has released these numbers to Fitch Ratings. Why? In light of the 38 Studios disaster we need to be far more open about sharing information! Here is the latest from Fitch posted today:

The Negative Outlook reflects T.F. Green's elevated risk profile resulting from multi-year traffic declines since peak level in fiscal 2005, down an aggregate 32% to 1.952 million enplanements in fiscal 2011. Increased activity from low-fare carriers at Boston Logan Airport contributed to year-over-year traffic losses of 8.8%, 10.5% and 3.6% in fiscal years 2009, 2010 and 2011, respectively. The first nine months of fiscal 2012 (through March) have shown signs of stability, with a marginal 0.1% increase over the same period in fiscal 2011.

The instrument landing glitch could have a much larger impact than this Beacon story indicates. When EDC attempts to float the new RIAC $48 million in bonds this fall the passenger numbers need to be up. Look at what Fitch Ratings says about the new bond issue:

"Fitch notes that additional debt to support the capital program would likely elevate the airport's already above average debt load. In light of the tepid trends in airport traffic, a rating action may be considered should any future borrowing be viewed to create added pressure to the airport's leverage or cost profile."

Do you really think that the ratings agencies are going to be happy with the RIAC bond offering now that 38 Studios hit the wall?

Traffic counts finally released on Friday afternoon. Enplanements down almost 6% from last April. Southwest down 8.41% or about two departures every day. May will probably not be much better due to the instrument approach problems.

I was VERY surprised by the April numbers!! I thought they would be much better...with School vacations! Total passengers down by 20,528...2011 vs. 2012 numbers!! I do not think they need to worry about the ILS being down...very temporary/GOOD reason for low passenger count!!

If you were a passenger on one of the diverted planes and you had a choice between Boston and Green for your next flight, which would you pick? RIAC's noise tracking system was down for months last year and now the ILS on the runway facing Airport Road went down for an extended period when the Category III ILS on the runway facing Main Avenue was also down because it "was being moved." Why did they move that ILS in May -- the foggy season when the water is colder than the air?

Look at the snow fence on Industrial Drive. It does not work because it is too close to the road. When I questioned this the answer I got was "don't worry about that. RIAC will plow the road if it needs to." The problem here is that snow fences serve two purposes -- to deal with visibility problems for drivers during strong winds and to cause the drifts to form on the side of the road, not in the middle of it. We don't all put snow tires on our cars that can deal with the resulting snow dumped right in the middle of the road 15 minutes after the plow goes by.

Leaving the snow fences next to the road rather than placing them where they used to be -- further back by the Indian Cemetery -- demonstrates the fact that RIAC simply does not get the most basic part of dealing with weather problems -- like the fogs of May and June.